KR100673680B1 - Diffraction optical element and method manufacturing the same, and optical device - Google Patents

Abstract

An object of the present invention is to provide a diffractive optical element, a method of manufacturing the same, and an optical device that can simultaneously realize a plurality of optical functions and are excellent in size and productivity. For this reason, the diffractive optical element 10 includes a plurality of layers 11 to 13, and each layer includes a multilayer member 10a made of an optical material. Adjacent layers 11 and 12 (12, 13) of the multilayer member are in close contact with each other and the refractive indexes of the optical materials are different from each other. Inside the multilayer member, adjacent interface surfaces 10b and 10c of adjacent layers are included. Of the three or more surfaces including the interface and the surface of the multilayer member, at least two surfaces are formed with uneven patterns 14 and 15 which cause a desired diffraction effect on the transmitted light, respectively. The shape or dimensions of the multilayer members are different from each other.

Description

Diffraction optical element and its manufacturing method, and optical device TECHNICAL FIELD

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase diffractive optical element, a method for manufacturing the same, and an optical apparatus that exhibit various optical functions by using diffraction phenomenon of light.

Diffraction optical elements are known as optical elements that exhibit various optical functions, such as lens functions (condensation and divergence), branching / multiplexing functions, light intensity distribution conversion functions, wavelength filter functions, and spectroscopic functions, using the diffraction phenomenon of light. have. Incidentally, a diffractive optical element having a spectroscopic function is also called a grating, and a diffractive optical element having a lens function is also called a zone plate.

The diffraction optical element of the phase type is formed by forming a diffraction grating uneven pattern on the surface of an optical material (for example, optical glass), and its optical function is determined by the shape of the uneven pattern. For example, in the case of grating such as a bias grating (Fig. 9), the uneven pattern is a straight line at equal intervals. In the case of the zone plate (Fig. 10), the uneven pattern is concentric.

In order to simultaneously realize a plurality of optical functions using a diffractive optical element, a method of preparing a plurality of diffractive optical elements having different single functions and arranging the plurality of diffractive optical elements in series is generally employed. According to this method, it is relatively easy to simultaneously realize a plurality of optical functions by the diffractive optical element.

However, in the method of arranging a plurality of diffractive optical elements having a single function in series, when the optical system composed of the plurality of diffractive optical elements is assembled, the alignment of each diffractive optical element must be precisely performed, resulting in high productivity. Can not. In addition, as the number of functions to be realized increases, the number of required diffractive optical elements also increases, making it difficult to manufacture with high precision by that amount, and also making it difficult to reduce the optical system.

Therefore, a method of synthesizing the uneven pattern with each of a plurality of optical functions to be realized simultaneously and forming it on one surface of the optical material has been proposed. This method is intended to realize a compact and multifunctional diffractive optical element, but since the uneven pattern after synthesis becomes a very complicated shape, it is difficult to precisely process one surface.

For example, in the case where the lens function and the spectroscopic function are to be realized simultaneously, the uneven pattern to be formed on one surface has a shape obtained by synthesizing the uniformly spaced linear pattern shown in FIG. 9 and the concentric circular pattern shown in FIG. do. Synthesis is performed by taking the sum of phase modulation by each pattern, and the shape of the concave-convex pattern after the synthesis is extremely complex and has low symmetry, as shown in FIG.

SUMMARY OF THE INVENTION An object of the present invention is to provide a diffractive optical element, a method for manufacturing the same, and an optical device that can simultaneously realize a plurality of optical functions and are excellent in productivity in a small size.

The diffraction optical element of the present invention comprises a plurality of layers, each layer comprising a multilayer member composed of an optical material, and the layers adjacent to the multilayer member are in close contact with each other, and the refractive indices of the optical materials are mutually different. The inside of the multilayer member is different, and at least two of the three or more surfaces in which the neighboring layers are in close contact with each other are included, and the one or more interfaces and the surface of the multilayer member are included in at least two surfaces. Each of the uneven patterns which cause a desired diffraction effect on the transmitted light is formed, and the uneven patterns formed on the other surface are different in shape or dimension with respect to the layer direction of the multilayer member.

In this diffractive optical element, since the incident light passes through the formation surface (at least two) of the uneven pattern sequentially and undergoes a plurality of diffraction operations, a plurality of optical functions can be simultaneously realized with one element. In addition, the diffractive optical element is compact and excellent in productivity.

Another diffractive optical element of the present invention comprises three or more layers, each layer comprising a multilayer member composed of an optical material, and adjacent layers of the multilayer member are in close contact with each other, and the refractive index of the optical material These are different from each other, and the two-layered member includes two or more intimate interfaces between adjacent layers, and at least two of the two or more interfaces each have an uneven pattern which causes a desired diffraction effect on the transmitted light. The concave-convex patterns formed on different surfaces are different in shape or dimension with respect to the layer direction of the multilayer member.

In this diffractive optical element, since the incident light passes through the formation surface (at least two) of the uneven pattern sequentially and undergoes a plurality of diffraction operations, a plurality of optical functions can be simultaneously realized with one element. In addition, since the uneven pattern is formed inside the multilayer member, the uneven pattern can be reliably protected. In addition, the diffractive optical element is compact and excellent in productivity.

Preferably, in the diffractive optical element of the present invention, the multilayer member includes two or more resin layers composed of optical materials made of resin, and at least two of the two or more resin layers closely adhere to each other at adjacent positions. At least one of the uneven patterns is formed on the interface between the resin layers in close contact with the neighboring positions.

In the method for manufacturing a diffraction optical element of the present invention, an uneven pattern causing a desired diffraction effect on transmitted light is formed in each of two adjacent layers, and the uneven patterns are diffracted in shape or dimension with respect to the layer direction. A method for manufacturing an optical element, comprising: a first step of forming a first uneven pattern on the surface of a layer made of a predetermined optical material, and an optical resin made of resin having a different refractive index from the optical material on the first uneven pattern A second step of forming a resin layer made of a material, and forming a second uneven pattern on the surface of the resin layer, wherein the second step is to provide an optical material of the resin on the first uneven pattern A first auxiliary step of applying an uncured material, a second auxiliary step of bringing the inverted shape of the second concave-convex pattern into close contact with the uncured material, and the mold in a state of being in close contact with the mold And a third auxiliary step of curing the uncured product.

Preferably, the method for manufacturing the diffractive optical element of the present invention is to harden the uncured product by light irradiation in the third auxiliary step.

An optical apparatus of the present invention includes the diffractive optical element, wherein the diffractive optical element is provided in a predetermined optical path of the optical device, and is provided in a direction in which the pattern formation surface intersects the optical path. Will be.

Preferably, the optical device of the present invention is a device using laser light, wherein the diffractive optical element is composed of an optical material in which each layer is transparent in the wavelength region of the laser light, and with respect to the optical path of the laser light. It is provided in the direction in which the forming surface intersects.

Also preferably, in the optical apparatus of the present invention, the wavelength region of the laser light used in the optical apparatus is an infrared wavelength region of 1.4 µm to 1.7 µm.

1 is a schematic diagram showing the overall configuration of the diffractive optical element 10 of the first embodiment.

2 is an optical path diagram illustrating an optical function of the diffractive optical element 10.

FIG. 3 is a diagram for explaining formation of the layer 12 and the uneven pattern 15 of the diffractive optical element 10.

4 is a schematic diagram showing the overall configuration of the diffractive optical element 20 of the second embodiment.

5 is a schematic diagram of a diffraction optical element having a (n + 1) layer structure.

6 is a schematic diagram of a diffraction optical element having a (n-1) layer structure.

FIG. 7 is a view for explaining a procedure for manufacturing the diffraction optical element 10 of the third embodiment.

8 is a schematic diagram of a diffraction optical element 40 of a modification.

FIG. 9 is a diagram showing the change in the lattice height in succession for each class for the grating uneven pattern exhibiting the spectral function.

Fig. 10 is a diagram showing the change in the lattice height in succession, divided by rank, for the uneven pattern of the zone plate having the lens function.

Fig. 11 is a diagram showing the change in the lattice height in succession by class for the uneven pattern after synthesis in the conventional multifunctional diffractive optical element.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail using drawing.

(1st embodiment)

As shown in FIG. 1, the diffraction optical element 10 of the first embodiment is constituted by one multilayer member 10a. The multilayer member 10a is composed of three layers 11, 12, and 13, and the layer 11 is an optical material having a low refractive index, and the layer 12 is an optical material having a high refractive index, and the layer 13. Is composed of an optical material of low refractive index. In other words, the layers 11 and 12 adjacent to the multilayer member 10a have different refractive indices, and the adjacent layers 12 and 13 also have different refractive indices.

In addition, the optical material which comprises the three layers 11-13 is an optical material which is transparent in the wavelength range of use of the diffraction optical element 10 (for example, infrared wavelength region of 1.4 micrometers-1.7 micrometers). . Specifically, of the three layers 11 to 13, the material of the layer 11 is optical glass, and the material of the layers 12 and 13 is optical resin. In short, the layer 11 is a glass layer, and the layers 12 and 13 are resin layers.

Here, as optical glass which is a material of the layer 11, the main components are SiO ₂ -PbO-R ₂ O, SiO ₂ -PbO-BaO-R ₂ O, SiO ₂ -B ₂ O ₃ -PbO-BaO, (SiO ₂ ) -B ₂ O ₃ -La ₂ O ₃ -PbO-Al ₂ O ₃ , (SiO ₂ ) -B ₂ O ₃ -La ₂ O ₃ -PbO-RO, (SiO ₂ ) -B ₂ O ₃ -La ₂ O ₃ -ZnO-TiO ₂ -ZrO ₂ , B ₂ O ₃ -La ₂ O ₃ -Gd ₂ O ₃ -Y ₂ O ₃ -Ta ₂ O ₅ , SiO ₂ -TiO ₂ -KF, SiO ₂ -B ₂ O Printed glass such as ₃ -R ₂ O-Sb ₂ O ₃ , B ₂ O _3- (Al ₂ O ₃ ) -PbO-RO, etc., the main component is SiO ₂ -RO-R ₂ O, SiO ₂ -BaO-R ₂ O , SiO ₂ -B ₂ O ₃ -BaO, (SiO ₂ ) -B ₂ O ₃ -La ₂ O ₃ -RO-ZrO ₂ , (SiO ₂ ) -B ₂ O ₃ -La ₂ O ₃ -ZnO-Nb ₂ O ₅ , B ₂ O ₃ -La ₂ O ₃ -Gd ₂ O ₃ -Y ₂ O ₃ , SiO ₂ -B ₂ O ₃ -R ₂ O-BaO, P ₂ O _5- (Al ₂ O ₃ -B ₂ Various glass materials, such as crown glass, quartz glass, fluorite, etc. which are O ₃ ) -R ₂ O-BaO, SiO ₂ -B ₂ O ₃ -K ₂ O-KF, and SiO ₂ -R ₂ O-ZnO, can be used.

As an optical resin which is a material of the layers 12 and 13, polycarbonate, polystyrene, polymethyl methacrylate, trifluoroethyl polymethacrylate, isobutyl polymethacrylate, methyl polyacrylate, diethylene glycol bis aryl carbonate , Polymethyl methacrylate, polyα-methyl bromide, polymethacrylic acid-2,3-dibrompropyl, aryl phthalate, phenyl polymethacrylate, polybenzoate, poly methacrylate pentacrolphenyl, polychrom In addition to styrene, polyvinyl naphthalene, polyvinylcarbazole, and silicone polymer, various resin materials and photopolymers classified into acrylic resins, urethane resins, epoxy resins, en-thiol resins, thiourethane resins, and the like can be used.

In the diffractive optical element 10, adjacent layers 11 and 12 of the multilayer member 10a are in close contact with each other, and adjacent layers 12 and 13 are also in close contact with each other. For this reason, the boundary surface 10b and the boundary surface 10c which are two boundary surfaces are contained in the multilayer member 10a.

On the two boundary surfaces 10b and 10c in the multilayer member 10a, the diffraction grating uneven patterns 14 and 15 are formed, respectively. These uneven patterns 14 and 15 differ from each other in shape and dimension with respect to the layer direction of the multilayer member 10a. In addition, a layer direction is two directions perpendicular | vertical to a lamination direction. The uneven pattern of the diffraction grating shape is a uneven pattern which causes a desired diffraction effect on the transmitted light.

The concave-convex patterns 14 and 15 will be described in detail. The concave-convex pattern 14 of the boundary surface 10b is a linear pattern of equal intervals in FIG. 9, and realizes a spectral function. The concave-convex pattern 15 of the interface 10c is a concentric circular pattern in Fig. 10, and realizes a lens function.

In other words, in the diffraction optical element 10 of the first embodiment, the lens function and the spectral function can be simultaneously realized with one element. For this reason, the light passing through the diffractive optical element 10 is collected by the lens function of the uneven pattern 15 as shown in FIG. 2, and the 0th order diffracted light by the spectroscopic function of the uneven pattern 14. It is divided into primary diffraction light and secondary diffraction light. Zero-shielding is light that goes straight along the optical axis. The primary light and the _secondary light are ... the light traveling in the directions of θ ₁ and θ ₂ . 2, only 0th order diffraction light, 1st order diffraction light, and 2nd order diffraction light are shown.

In order to realize good optical performance, each lattice plane spacing D ₁ is preferably shorter, and is preferably 1 mm or less, more preferably 500 μm or less. If the lattice spacing D ₁ is larger than this, the light is bent in an unintended direction, so the flare increases. In view of optical performance, the shorter the lattice plane spacing D ₁ is, the better, but considering the ease of manufacture, it is preferable that the distance between the lattice planes is 5 μm or more, and further, about 10 μm. Also, the lattice plane spacing D _{1 corresponds} to the interval between the _top of a certain lattice (the uneven pattern 14) and the valley portion of the lattice (the uneven pattern 15) stacked thereon.

In addition, the grating height H ₁ of the uneven pattern 14 is determined according to the refractive index difference between adjacent layers 11 and 12, and the grating height H ₂ of the uneven pattern 15 is adjacent to the layers 12 and 13. ) Is determined according to the difference in refractive index between them. The grid heights H ₁ and H ₂ correspond to the height difference between the concave and convex portions of the uneven patterns 14 and 15.

In general, when considering a diffraction grating uneven pattern having the same optical function, the difference in refractive index between adjacent layers and the grating height of the uneven pattern are in inverse proportion. In other words, when the refractive index difference is increased, the grid height can be lowered. When the refractive index difference is small, the grid height must be increased.

In view of the processing precision of the uneven patterns 14 and 15, the lower the grid heights H ₁ and H ₂ of the uneven patterns 14 and 15 are preferable. Moreover, it is preferable to make it low also at the point of reducing the bad influence to the image by the light which inclines with respect to an optical axis. In order to make the grating heights H ₁ and H ₂ within the practical range (in order to process the uneven patterns 14 and 15 with high precision), it is preferable that the refractive index difference between neighboring layers 11 and 12 and 12 and 13 is 0.01 or more. Do.

The procedure for manufacturing the diffractive optical element 10 of the first embodiment is outlined as follows. The uneven | corrugated pattern 14 is formed in the << 11 >> layer 11 surface. << 12 >> The layer 12 is formed on the uneven pattern 14, and the uneven pattern 15 is formed on the surface of the layer 12. << 13 >> The layer 13 is formed on the uneven pattern 15.

Formation of the uneven | corrugated pattern 14 in said procedure << 11 >> is processing with respect to the glass layer (layer 11). As the processing method, any of the following three methods (A) to (C) can be used, for example.

(A) The glass layer is directly processed by mechanical processing such as cutting, grinding, or CVD (Chemical Vaporization Machining) to form the uneven pattern 14 on the surface. (B) A resist layer finely processed by photolithography is formed on the glass layer, and then, by ion etching, the pattern shape of the resist layer is transferred to the glass layer, thereby forming the uneven pattern 14 on the surface. .

(C) The pattern shape is transferred to a glass layer using molds, such as a metal mold | die, and the uneven | corrugated pattern 14 is formed in the surface (glass molding method). In this method, when the low melting point glass whose yield point is 500 degrees C or less is used as an optical material of a glass layer, the temperature at the time of shaping | molding can be lowered and the restriction | limiting regarding the heat resistance of a metal mold | die can be alleviated. For this reason, the metal material which can be easily processed by cutting or reduction can be used as a material of a metal mold | die.

Even if any one of these three methods (A) to (C) is used, the uneven pattern 14 is a simple equally spaced linear pattern as shown in Fig. 9, so that the glass layer (layer 11) ) Can be processed easily and with high precision.

Formation of the uneven | corrugated pattern 15 in said procedure << 12 >> is a process with respect to the resin layer (layer 12). As the processing method, for example, any one of the following three methods (D) to (F) can be used.

(D) The uneven pattern 15 is transferred to the surface by the injection molding method. (E) The pattern shape is transferred to a resin layer using molds, such as thermosetting or photocurable resin, and a metal mold | die, and the uneven | corrugated pattern 15 is formed in the surface. (F) In the case where the resin layer is a photopolymer, the uneven pattern 15 is formed on the surface by irradiating interference light to produce a hologram.

Here, method (E) is demonstrated in detail using FIG.3 (a)-(c). First, the uncured material 12a of the resin material is applied on the uneven pattern 14 of the glass layer (layer 11) (a). Next, the mold 16 of the inverted shape (hereinafter referred to as 'inverted pattern 15a') of the uneven pattern 15 formed therefrom is brought into close contact with the uncured product 12a (b), and the mold 16 is formed. The uncured product 12a is filled between the layer 11 and the layer 11.

At this time, it is preferable to press and unfold so that the uncured material 12a may enter according to the minute recesses of the uneven pattern 14 of the layer 11 and the inverted pattern 15a of the mold 16. Then, in the state after being pushed out, the uncured product 12a is cured by irradiating or heating light (for example, ultraviolet rays) on the side of the layer 11. Finally, mold release (c). As a result, the resin layer (layer 12) is formed on the uneven pattern 14, and the uneven pattern 15 is formed on the surface of this layer 12.

Even if any one of these three methods (D) to (F) is used, since the uneven pattern 15 is a simple concentric circular pattern as shown in FIG. 10, the surface of the resin layer (layer 12) On the contrary, it can be processed easily and with high precision.

On the other hand, in the above-mentioned << 13 >>, formation of the layer 13 does not have an uneven | corrugated pattern instead of the mold | type 16 which has the inversion pattern 15a in the method (E) shown in FIG. By using a flat die, the same can be done.

As a result, it is possible to easily obtain the diffractive optical element 10 in which two simple uneven patterns 14 and 15 are sequentially formed inside the multilayer member 10a. As described above, the diffractive optical element 10 can realize the lens function and the spectroscopic function simultaneously with one element, and is extremely small. That is, according to the first embodiment, the lens function and the spectroscopic function can be simultaneously realized, and the diffraction optical element 10 which is small in size and excellent in productivity can be easily obtained.

(2nd embodiment)

The diffraction optical element 20 of 2nd Embodiment is comprised by one multilayer member 20a, as shown to FIG. 4 (a), (b). Moreover, this multilayer member 20a consists of four layers 21, 22, 23, and 24, and the refractive indexes of adjacent layers 21, 22, 22, 23, 23, and 24 differ from each other. The optical material of the layers 21-24 is determined so that it may be. Either of the optical materials of the layers 21 to 24 is an optical resin that is transparent in the wavelength region of use of the diffractive optical element 20. Moreover, the specific example of optical resin is the same as that of the layers 12 and 13 mentioned above.

In the diffractive optical element 20, the layers 21, 22, 22, 23, 23, 24 adjacent to the multilayer member 20a are in close contact with each other. For this reason, the boundary surfaces 20b, 20c, and 20d are included in the multilayer member 20a.

On the three boundary surfaces 20b, 20c, and 20d in the multilayer member 20a, the diffraction grating uneven patterns 25, 26, 27 are formed, respectively. These uneven patterns 25, 26, and 27 differ from each other in shape and dimension with respect to the layer direction of the multilayer member 20a.

The concave-convex patterns 25, 26, and 27 will be described in detail. The concave-convex patterns 25 and 27 of the boundary surfaces 20b and 20d are all linearly-shaped patterns of equal intervals in FIG. . However, the orientations of the uneven patterns 25 and 27 are rotated by 90 degrees about the stacking direction. The concave-convex pattern 26 of the boundary surface 20c is a concentric circular pattern in Fig. 10, and realizes a lens function.

In other words, in the diffraction optical element 20 of the second embodiment, one element can simultaneously realize a lens function and two kinds of spectroscopic functions. For this reason, the light passing through the diffractive optical element 20 is collected by the lens function of the uneven pattern 26, and the two types of zero-order diffraction light and the first order by the spectroscopic functions of the uneven patterns 25 and 27. It is divided into diffracted light and secondary diffracted light.

In addition, the procedure for manufacturing the diffractive optical element 20 is outlined as follows. The uneven pattern 25 is formed on the surface of the << 21 >> layer 21. << 22 >> The layer 22 is formed on the uneven pattern 25, and the uneven pattern 26 is formed on the surface of the layer 22. << 23 >> The layer 23 is formed on the uneven pattern 26, and the uneven pattern 27 is formed on the surface of the layer 23. << 24 >> The layer 24 is formed on the uneven pattern 27.

As described above, since the layers 21 to 24 of the diffractive optical element 20 are both made of optical resins, each of the procedures << 21 >> to << 23 >> is described above. 10) The procedure of manufacturing << 12 >> is repeated, and the sequence << 24 >> is the same as the above-mentioned << 13 >>.

As a result, the diffractive optical element 20 in which three simple uneven | corrugated patterns 25-27 were formed in order inside the multilayer member 20a can be obtained easily. As described above, the diffractive optical element 20 can realize a lens function and two kinds of spectroscopic functions simultaneously with one element, and is extremely small. That is, according to the second embodiment, the lens function and the two kinds of spectroscopic functions can be simultaneously realized, and the diffraction optical element 20 which is small in size and also excellent in productivity can be easily obtained.

Incidentally, in the above-described first and second embodiments, the diffraction optical elements 10 and 20 of the three-layer structure and the four-layer structure have been described as an example, but the present invention is also applied to the diffraction optical element having a five-layer or more multilayer structure. Applicable However, regardless of the number of layers in the multilayer structure, the optical material of each layer must be determined so that the refractive indices of neighboring layers are different from each other. It is also necessary to bring adjacent layers into close contact with each other.

As shown in FIG. 5, when the diffractive optical element has a (n + 1) layer structure, n close contact surfaces between adjacent layers are included in the multilayer member, whereby n kinds of different uneven patterns are formed. You can do it. That is, with one diffractive optical element, n kinds of optical functions can be realized simultaneously.

In addition, the optical function which can be realized by the diffractive optical element is not limited to the combination of the lens function and the spectroscopic function. By changing the shape or dimension of the concave-convex pattern formed in the interface between neighboring layers, it is possible to realize various optical functions such as branch / harmonic function, light intensity distribution conversion function, wavelength filter function, and spectroscopic function. Do. Incidentally, a desired function can be obtained by forming a concave-convex pattern that is simple and easy to form at the time of manufacture without forming a concave-convex pattern of a complicated shape in order to realize a desired function.

In addition, since the shape of the n uneven patterns to be formed inside the multilayer member is simply symmetrical regardless of the number of layers (that is, the number of uneven patterns) of the multilayer structure of the diffractive optical element, these uneven patterns are described in detail. By sequentially forming by any of the methods (A) to (F), a multifunctional and compact diffraction optical element can be easily obtained.

In order to form the diffractive optical element as described above, at least two types of optical materials having different refractive indices are required regardless of the number of layers (ie, the number of irregularities) of the multilayer structure of the diffractive optical element. In the case of using two types of optical materials, the refractive indices of neighboring layers can be different from each other by alternately laminating one optical material and the other optical material.

Further, in the above-described embodiment, the diffraction grating irregularities pattern is formed on the interface between neighboring layers inside the diffractive optical element, but the same irregularities may be formed on the surface of the diffractive optical element. The surface of the diffractive optical element is an interface between the layers at both ends and the surrounding atmosphere (for example, air), and usually has different refractive indices.

As shown in Fig. 6, when the diffractive optical element has a (n-1) layer structure, since there are (n-2) boundary surfaces between two neighboring layers therein and two surfaces, n is provided at the boundary surface and the surface. It is possible to form different uneven patterns of a kind. That is, with one diffractive optical element, n kinds of optical functions can be realized simultaneously. However, in consideration of the protection of the uneven pattern, it is preferable to form the inner surface of the uneven optical element.

In addition, since the diffraction optical elements of the present invention are each multifunctional and compact, as described above, they can be easily installed in various optical devices. When installed in the optical device, the diffractive optical element is provided in a predetermined optical path of the optical device, and is provided in a direction in which the formation surface of the uneven pattern crosses the optical path.

In particular, when incorporated into an optical device using a laser beam, the diffraction optical element is provided in a direction in which the formation surface of the uneven pattern crosses the optical path of the laser beam. In addition, it is preferable that each layer of the diffractive optical element is made of an optical material that is transparent in the wavelength region of the laser light.

Moreover, in optical devices (relays, splitters, etc.) in the field of optical communication, since the multifunction, miniaturization, and thinning of optical elements are strongly demanded, it is particularly useful to assemble the diffraction optical element of the present invention in such an optical device. . In the optical apparatus in this optical communication field, laser light of an infrared wavelength region (1.4 m to 1.7 m) is used.

For example, when the diffraction optical element 10 shown in Figs. 1 and 2 is assembled into an optical apparatus used for optical communication, zero-order light is spotted in the optical system at the rear end among the light transmitted through the diffraction optical element 10. to be joined at the same time, for example, primary light (light of θ ₁ direction) as that can be picked up as the monitoring. This is because the primary light forms spots different for each wavelength by the spectroscopic function of the diffractive optical element 10.

(Third embodiment)

3rd Embodiment of this invention shows the diffraction optical element 10 (FIG. 1) of 1st Embodiment mentioned above more specifically. Here, one specific composition of the multilayer member 10a of the diffractive optical element 10 will be described, and its configuration and manufacturing procedure will be described.

In 3rd Embodiment, the low melting-point glass P-SK60 (nd = 1.591, At (break point) = 404 degreeC) made from Sumida optical glass was used as an optical material of the layer 11, and the layer 12 was used. ), An urethane acrylate ultraviolet curable resin (nd = 1.554) was used as the optical material of the layer 13, and as the optical material of the layer 13, a fluorine-containing methacrylate ultraviolet curable resin (nd = 1.505) was used. These are laminated sequentially.

In addition, the irregular portion 14, the grating height H ₁ is 15.88㎛, 17㎛ pitch (equal intervals) formed in the adjacent boundary surfaces (10b) between the layers (11, 12) for the multi-layer member (10a). The uneven pattern 15 formed in the interface 10c between adjacent layers 12 and 13 has a grid height H ₂ of 11.99 µm and a pitch of 187.8 µm (center) to 5.0 µm (the outermost circumference). The surface spacing D ₁ of the uneven patterns 14 and 15 is 30 μm.

The procedure of manufacturing the diffraction optical element 10 of this 3rd Embodiment is the same as the procedure << 11 >>-<< 13 >> which was outlined and demonstrated in 1st Embodiment mentioned above. In addition, in the order << 11 >>, the glass molding method of the said method (C) is used (FIG. 7 (a)), and in the order << 12 >>, the said method (E) is used (FIG. 7 (b) ), And the method (E) is used also in the procedure << 13 >> (FIG. 7 (c)). The details of the method (E) are as shown in Figs. 3 (a) to (c).

First, the procedure << 11 >> which manufactures the diffraction optical element 10 of 3rd Embodiment is demonstrated. In this procedure << 11 >>, as shown to Fig.7 (a), two metal molds 31 and 32 are used. Here, one mold 31 is formed with an inverted shape of the uneven pattern 14 (hereinafter referred to as 'inverted pattern 14a'), and the other mold 32 has a flat plate shape having no uneven pattern. to be.

Preparation of the metal mold | die 31 is performed as follows. Using a stavax material 31a as a mold material, first, a Ni-P plating layer 31b having a thickness of about 150 mu m is formed thereon by an electroless plating method. Next, this Ni-P plating layer 31b is processed by cutting to form an inversion pattern 14a.

In the order << 11 >> using the two molds 31 and 32, two optical materials (low melting point glass P-SK60) of the layer 11 were heated in a nitrogen atmosphere (up to 420 ° C). The molds 31 and 32 are sandwiched and pressed. Thereby, the uneven | corrugated shape of the inversion pattern 14a of the metal mold 31 is transferred to the surface of the optical material of the layer 11 (glass molding method). After that, the uneven pattern 14 is formed on the surface of the layer 11 by the mold release (state of FIG. 7A).

Next, a procedure << 12 >> of manufacturing the diffraction optical element 10 of the third embodiment will be described. In this procedure << 12 >>, as shown to FIG. 7 (b), one metal mold | die 33 is used. In this mold 33, an inversion pattern 15a corresponding to the inverted shape of the uneven pattern 15 is formed.

Preparation of the metal mold | die 33 is performed similarly to preparation of the metal mold 31 mentioned above. First, the Ni-P plating layer 33b (thickness is about 150 µm) is formed on the star box material 33a, which is a mold material, and then the Ni-P plating layer 33b is processed by cutting to invert the pattern. (15a) is formed.

In the procedure << 12 >> using the mold 33, the optical material (urethane acrylate-based ultraviolet curable resin of the layer 12) on the uneven pattern 14 formed in the above procedure << 11 >>. ), The uncured resin is added dropwise, and the mold 33 is brought close to this, and the uncured resin is filled between the mold 33 and the layer 11. Next, ultraviolet rays are irradiated from the back surface side of the layer 11 to cure the optical material of the layer 12. Thereby, the uneven shape of the inversion pattern 15a of the metal mold 33 is transferred to the surface of the layer 12. Thereafter, the mold is released to form the uneven pattern 15 on the surface of the layer 12 (state of FIG. 7B).

Finally, the procedure << 13 >> which manufactures the diffraction optical element 10 of 3rd Embodiment is demonstrated. In this procedure << 13 >>, as shown to Fig.7 (c), one metal mold | die 34 is used. This mold 34 is a flat plate shape having no uneven pattern.

In the procedure << 13 >> using the mold 34, the optical material (fluorine-containing methacrylate-based ultraviolet light) of the layer 13 is formed on the uneven pattern 15 formed in the above procedure << 12 >>. The uncured resin of cured resin) is added dropwise, and the mold 34 is brought close to each other to fill the uncured resin between the mold 34 and the layer 12. Next, ultraviolet rays are irradiated from the back surface side of the layer 11 to cure the optical material of the layer 13. As a result, the planar shape of the mold 34 is transferred to the surface of the layer 13. Thereafter, by releasing, the surface of the layer 13 becomes planar (state of Fig. 7 (c)).

In this manner, the diffractive optical element 10 of the third embodiment can be obtained in which two uneven patterns 14 and 15 are sequentially formed inside the multilayer member 10a. As described above, the diffractive optical element 10 can realize the lens function and the spectroscopic function simultaneously with one element.

In addition, in the above << 11 >> to << 13 >> of 3rd Embodiment, formation of the uneven | corrugated patterns 14 and 15 of the diffraction optical element 10 is the metal mold | die 31 manufactured previously, respectively. And 33), the inversion patterns 14a and 15a can be transferred easily.

In addition, the production of the molds 31 and 33 is easy. This means that the inversion pattern 14a of the mold 31 is a simple equally spaced linear pattern, the inversion pattern 15a of the mold 33 is also a simple concentric circular pattern, and the Ni-P plating layers 31b and 33b This is because cutting can be easily performed with high precision.

Therefore, according to the third embodiment, the lens function and the spectroscopic function can be simultaneously realized (multifunction), and the diffraction optical element 10 which is small in size and also excellent in productivity can be easily manufactured.

(4th Embodiment)

4th Embodiment of this invention shows the diffraction optical element 20 (FIG. 4) of 2nd Embodiment mentioned above more specifically. Here, one specific composition of the multilayer member 20a of the diffractive optical element 20 will be described, and its configuration and manufacturing procedure will be briefly described.                 

In the fourth embodiment, as the optical material of the layer 21 and the layer 23, a mixture (nd = 1.490) of a six-functional urethane acrylate and isobornyl methacrylate is used. (21) and 4 layers of these are alternately laminated | stacked using the ethoxylated bisphenol A dimethacrylate (nd = 1.541) as an optical material of the layer 24.

In addition, the uneven pattern 25 formed on the boundary surface 20b between the layers 21 and 22 of the multilayer member 20a and the uneven pattern formed on the boundary surface 20d between the adjacent layers 23 and 24 ( 27 is in the same shape as the uneven pattern 14 of the above-described third embodiment, and its orientation is rotated by 90 degrees. The uneven | corrugated pattern 26 formed in the boundary surface 20c between adjacent layers 22 and 23 is the same shape as the uneven | corrugated pattern 15 of 3rd Embodiment mentioned above.

The procedure of manufacturing the diffraction optical element 20 of this 4th embodiment is the same as the procedure << 21 >>-<< 24 >> which was outlined and demonstrated in 2nd Embodiment mentioned above. In addition, in steps << 21 >> to << 23 >>, the same process as that of step << 12 >> in the above-described third embodiment is used to form an inverted mold of the uneven patterns 25 to 27 to be formed. Each use is repeated three times, changing sequentially. And the last procedure << 24 >> is performed using the flat metal mold | die similar to the procedure << 13 >> of 3rd Embodiment mentioned above.

In this manner, the diffractive optical element 20 of the fourth embodiment can be obtained in which three uneven patterns 25 to 27 are sequentially formed inside the multilayer member 20a. As described above, the diffractive optical element 20 can realize a lens function and two kinds of spectroscopic functions simultaneously with one element.

In addition, in the procedure << 21 >>-<< 24 >> of 4th Embodiment mentioned above, formation of the uneven | corrugated patterns 25-27 of the diffraction optical element 20 uses the metal mold | die manufactured previously, respectively. This can be done easily by transferring the inversion pattern. In addition, the inversion pattern of a metal mold | die is a simple equally spaced linear pattern and a concentric circular pattern, and manufacture of a metal mold | die can also be made easy and high precision.

Therefore, according to the fourth embodiment, the lens function and the two kinds of spectroscopic functions can be simultaneously realized (multifunction), and the diffraction optical element 20 which is small in size and also excellent in productivity can be easily manufactured.

In the above-described embodiments and examples, the diffraction optical elements 10 and 20 constituted by one multilayer member 10a or 20a have been described as an example, but the present invention is not limited thereto. For example, like the diffractive optical element 40 shown in FIG. 8, two multilayer members 40a and 40b can also be provided.

The multilayer member 40a of the diffractive optical element 40 has a two-layer structure, and the diffraction grating irregularities (patterns) are formed on the interface between adjacent layers 41 and 42 and the surface of the layer 42, respectively. 1, 2)) are formed. The multilayer member 40b also has a two-layer structure, and diffraction grating uneven patterns (patterns 3 and 4) are formed on the interface between neighboring layers 43 and 44 and the surface of layer 43, respectively. Is formed.

In this diffraction optical element 40, the surface (pattern 2) of the layer 42 and the surface (pattern 3) of the layer 42, in other words, between the two multilayer members 40a and 40b. The optical material 46 is filled by the sealing member 45 between the and. The sealing member 45 also plays a role of integrating the two multilayer members 40a and 40b by adhesive rubber or the like.                 

Since the optical material 46 is a gas or liquid different from the neighboring layers 42 and 43 and is sealed by the sealing member 45, it is considered that there is almost no uneven internal refractive index.

As the liquid as the optical material 46, for example, in addition to a general solvent classified into pure water, alcohols, ethers, esters, etc., the refractive index (refractive index used in the immersion observation of a microscope, etc. is already known) Liquid) can be used. The refraction liquid is bromonaphthalene, dinbutyl sebacinate, or the like. In addition to the air, an inert gas such as nitrogen or argon can be used for the gas as the optical material 46.

According to the present invention, a plurality of diffractive optical elements can simultaneously realize a plurality of optical functions and can be easily produced.

Claims (8)

Composed of a plurality of layers, each layer having a multilayer member composed of an optical material, Adjacent layers of the multilayer member are in close contact with each other, and the refractive indexes of the optical materials are different from each other, One or more intimate interfaces between the adjacent layers are included in the multilayer member, In at least two of the three or more surfaces including the one or more boundary surfaces and the surface of the multilayer member, an uneven pattern causing a desired diffraction effect on the transmitted light is formed, respectively, The uneven patterns formed on different surfaces are different in shape or dimension with respect to the layer direction of the multilayer member. Consisting of three or more layers, each layer having a multilayer member composed of an optical material, Adjacent layers of the multilayer member are in close contact with each other, and the refractive indexes of the optical materials are different from each other, Two or more intimate interfaces between adjacent layers are included in the multilayer member, At least two of the two or more boundary surfaces are each provided with an uneven pattern which causes a desired diffraction effect on the transmitted light, The uneven patterns formed on different surfaces are different in shape or dimension with respect to the layer direction of the multilayer member. The said multilayer member of Claim 1 or 2 contains 2 or more resin layers comprised from the optical material made of resin, At least two of the two or more resin layers are in close contact with each other at neighboring positions, At least one of the uneven patterns is formed on the interface between the resin layers in close contact with the adjacent position. In each of the two adjacent layers, a concave-convex pattern causing a desired diffraction effect on the transmitted light is formed, and the manufacturing method of the diffractive optical element having different shapes or dimensions of the concave-convex patterns with respect to the layer direction, A first step of forming a first uneven pattern on the surface of a layer made of a predetermined optical material, A second step of forming a resin layer made of a resin optical material having a refractive index different from that of the optical material on the first uneven pattern, and forming a second uneven pattern on the surface of the resin layer, The second step includes a first auxiliary step of applying an uncured material of the optical material made of resin on the first uneven pattern, and a second contacting shape of the inverted shape of the second uneven pattern against the uncured material. And an auxiliary step, and a third auxiliary step of curing the uncured material in a state in which the mold is in close contact with the mold. The method of manufacturing a diffractive optical element according to claim 4, wherein in said third auxiliary step, said uncured product is cured by light irradiation. An optical device comprising the diffractive optical element according to claim 1 or 2, The diffraction optical element is provided in a predetermined optical path of the optical device, and is further provided in a direction in which the formation surface of the uneven pattern crosses the optical path. 7. The optical device according to claim 6, wherein the optical device is a device using a laser beam, The diffraction optical element is characterized in that each layer is made of an optical material transparent in the wavelength region of the laser light, and further provided in a direction in which the forming surface intersects with respect to the optical path of the laser light. 8. The optical apparatus according to claim 7, wherein the wavelength region of the laser light used in the optical apparatus is an infrared wavelength region of 1.4 µm to 1.7 µm.

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